1. Field of the Invention
The present invention relates to a linear and flexible article designed to pull in and dispose through a protective conduit a cable such as a power cable, a telephone line or an optical-fiber cable. The linear articles of this kind are called "hauling cords" or "fish tapes" in the industries (and the former name will be used herein).
2. Prior Art
FIG. 10 shows a typical example `T` of such hauling cords, as disclosed in the Japanese Utility Model Publication No. Sho.61-22424 (issued in 1986). This hauling cord `T` usually consists of three extruded and drawn polyester resin filaments 01, wherein these filaments have been intertwisted and simultaneously hot set to permanently maintain their twisted configuration like a three-ply thread. Another Utility Model Publication No. Hei. 4-16566 (issued in 1992) discloses a modified hauling cord. The three filaments constituting this intertwisted hauling cord are bonded together along and at their regions that are in contact with each other, to thereby provide a substantially integral linear member.
FIG. 11 illustrates how to use such an intertwisted hauling cord `T`. A flexible wire `Y` may be connected at its one end by a cylindrical joint `S` to one end of the hauling cord. A guiding end `G` having a hole `h` for holding the cable may be attached to the other end of the relatively short flexible wire `Y`, to thereby form a finished hauling cord for commercial and practical use. However for the purpose of simpler and concise description, the unfinished cords to which any additional wire etc. have not yet been attached will herein be referred to simply as "hauling cords".
Those three-ply type prior art hauling cords `T` have been employed long, widely and conveniently since the application date of the first mentioned Utility Model first mentioned above. However, the protective conduits for the various cables have recently been increasing their length and nowadays those conduits are often bent in a complicated fashion. As a result, it has been required these days not only to elongate each hauling cord but also to render same lighter in weight and easier to use and improve its compression strength as well as its tensile strength.